Question

高中英语中can与may，could、might、may、would/+have done 的区别

Answer 1

情态动词加have done都是对过去事情的推测，区别只在于情态动词的不同

一、 “must+have+done”
表示对过去事情的肯定推测，译成“一定做过某事”，该结构只用于肯定句。

1. It must have rained last night, for the ground is wet. 昨晚一定下雨了，因为地面还是湿的。

2. You must have been mad to speak to the servant. 你和仆人说话，一定是发疯了。
二、 “can't+have+done”
表示对过去事情的否定推测，译成“不可能做过某事”。

1. Mr. Smith can‘t have gone to Beijing, for I saw him in the library just now. 史密斯先生不可能去北京了，我刚才还在图书馆见过他。

2. Mary can't have stolen your money. She has gone home. 玛丽不可能偷你的钱，她回家去了。
三、 “can+have+done”
表示对过去行为的怀疑，用于疑问句，译成“可能做过……吗？”。

1. There is no light in the room. Can they have gone out? 屋里没有灯，他们可能出去了吗？

2. There is nowhere to find them. Where can they have gone? 到处找不到他们，他们可能到什么地方去呢？
四、 “could+have+done”
是虚拟语气，表示对过去事情的假设，意思是本来能够做某事而没有做。

He could have passed the exam, but he was too careless. 本来他能够通过考试，但是他太粗心。
五、 “may+have+done”
表示对发生过的事情的推测，意思是“可能已经”或“也许已经”，用于肯定句中。

—What has happened to George?
—I don't know. He may have got lost.
—乔治发生了什么事？
——我不知道，他可能迷路了。
六、 “might+have+done”
表示对过去事情的推测，might与may意思相同，但可能性更小。多用于虚拟语气结构中。

1. He might have given you more help, even though he was busy. (MET90) 他或许会多给你一些帮助，即使他很忙。
2. She might have achieved greater progress, if you had given her more chances. 如果你多给她点机会，她可能已经取得更大的成绩。
七、 “would+have+done”
虚拟语气，表示对过去事情的假设，意思是“本来会做”。

1. I would have told you all about the boy's story, but you didn't ask me. 我本来会告诉你这个小男孩的故事，但是你没有问我。
2. Without your help, I wouldn't have achieved so much. 没有你的帮助，我是不会取得如此大的成绩。
八、 “should+have+done”
意思是“本来应该做某事，而实际没做。” “shouldn‘t+have+done”表示本来不应该做某事，而实际做了。含有指责对方或自责的含意。

1. Tom, you are too lazy. The work should have been finished yesterday. 汤姆，你太懒惰了，这项工作本来应该昨天就做完的。
2. Look, Tom is crying. I shouldn't have been so harsh on him. 看，汤姆哭了，我本来不应该对他如此严厉。
九、 “ought to+have+done”
表示过去应该做而实际并没有做，译成“理应做……”，往往表示遗憾。与“should+have+done”用法基本一样。

I ought to have gone home last Sunday. 我理应上星期日回家。

You ought not to have given him more help. 你不应该帮助他那么多。
十、 “need+have+done”
表示本来需要做某事而没有做。“needn‘t+have+done”则表示“本来不需要做某事而做了”。

I needn‘t have bought so much wine—only five people came. 我本来没有必要买这么多酒，只来了五个人。

He need have hurried to the station. In that case, be wouldn't have missed the train. 他本来需要快点去车站，那样的话，他就不会误了火车。